Correction: Optimizing psychotherapy dosage for comorbid depression and personality disorders (PsyDos): a pragmatic randomized factorial trial using schema therapy and short-term psychodynamic psychotherapy (BMC Psychiatry, (2018), 18, 1, (252), 10.1186/s12888-018-1829-1)

Following publication of the original article [1], the author identified errors in block randomization and sample size. The correct sentence of block randomization and sample size is given below. Block randomization The sentence currently reads: Patients will then be randomized by one of two research department employees in one of four groups (with a 1:1:1:1 allocation) using a computer script performing block randomization (25 vs 50-sessions; ST vs SPSP). The sentence should read: Patients will then be randomized by one of two research department employees in one of four groups (with a 1:1:1:1 allocation) with random allocation sequences that were generated using the SPSS random number generator (SPSS, Chicago). Sample size The sentence currently reads: According to this effect size (and given our choices of α = 0.05, two-tailed, power (1-β) = 0.80) 78 patients are needed in both dosage-groups. When 25% dropout is taken into account at least 200 patients will be needed for inclusion. The sentence should read: According to this effect size (and given our choices of α = 0.05, two-tailed, power (1-β) = 0.80) 79 patients are needed in both dosage-groups. When 25% dropout is taken into account at least 211 patients will be needed for inclusion.